Joseph Irwin Miller (May 26, 1909 – August 19, 2004) was an American industrialist, patron of modern architecture, and lay leader in the Christian ecumenical movement and civil rights. He was instrumental in the rise of the Cummins Corporation and giving his hometown of Columbus, Indiana international stature with its buildings.

On February 5, 1943, he married Xenia Simons.[1] They had three daughters, Margaret, Catherine, Elizabeth, and two sons Hugh and William. He had ten grandchildren, Jonathan, Zachary, Joshua, Benjamin, Aaron, Andrew, AnnaCatherine, Katherine, Laura, and Emily.

The Miller House which was designed by Eero Saarinen, was declared a U.S. National Historic Landmark in 2000. In 2010, after the death of Mrs. Miller, the house was donated to the Indianapolis Museum of Art. The family's Canadian summer home on Lake Rosseau in Windermere, Ontario was also designed by Saarinen.

Miller joined Cummins, the family business, in 1934. He was executive vice president from 1944 to 1947, president from 1947 to 1951, and chairman from 1951 to 1977. He served as a lieutenant in the U.S. Navy in the South Pacific during the Second World War.

In 1950, Miller helped to establish the National Council of Churches (NCC) and later served as its first lay president (1960–63). Miller chaired the NCC's Commission on Religion and Race, which coordinated organized religion’s support for strong civil rights legislation, and jointly sponsored the March on Washington. He led religious delegations that met with Presidents John F. Kennedy and Lyndon Johnson to push for the legislation that became the Civil Rights Act of 1964.

Miller served as a Trustee of the Ford Foundation and Yale University, and as a director of Chemical Bank. He established the Irwin-Sweeney-Miller Foundation, which supports numerous charities and institutions—notably, Christian Theological Seminary in Indianapolis and Emma Willard School, a leading girls' preparatory school in Troy, NY. The family's business interests were widespread, and he served at various times as Chairman of Irwin Union Bank in Columbus IN, Union Starch and Refining Company, and Irwin Management Company.

Irwin Management was the family's private wealth-management and services organization, funded from Mr. Miller's large Cummins Engine Co. dividends and from the income generated by other holdings. The group managed all of the family's assets except Cummins Engine—which Mr. Miller managed personally, as President and later as Chairman. IMCO, as it was called, was divided into departments for Marketable Securities, Oil and Gas, Real Estate, Venture Capital, Financial Planning and Analysis, and Family Services. The company was staffed by about 20 professionals, many of whom had MBA degrees from the leading graduate business schools (e.g., Harvard, Columbia, Chicago, Carnegie-Mellon, Stanford, Oxford). In addition to financial management, the company provided staff services to assist Mr. Miller's roles in philanthropic, foundation, directorship, and trustee positions. It was considered a high-status firm among MBA students, and there was spirited competition for jobs at IMCO upon graduation.

Upon Miller's death in 2004, the National Council of Churches of Christ in the USA instituted an annual J. Irwin Miller Award. The award is presented annually to "a lay person who has been a witness, through action in the world, to justice and other values affirmed by Christian faith, and who has demonstrated a commitment to church unity."[3]